Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Piezoelectric crystal testing
Patent
1990-01-12
1992-05-26
Wieder, Kenneth A.
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Piezoelectric crystal testing
310316, G01R 2702
Patent
active
051171929
ABSTRACT:
A monitoring circuit monitors a piezoelectric crystal for changes in its resonant frequency as a film of material is vacuum deposited on it, e.g. to control a source of vapors of the material. A controllable frequency generator generates a drive signal of a accurately known frequency and phase within a band of RF frequencies that includes the resonant frequency of the crystal. The RF signal is applied through a duplexing circuit to the crystal, and a response signal is applied through the duplexing circuit to a signal amplifier and limiter circuit to a phase detector. The phase detector is also supplied with the RF drive signal, and has a phase output signal which is zero when the crystal is at resonance, and is negative or positive when the applied RF signal is below or above resonance, respectively. A micro-controller can be employed for controllably sweeping the frequency of the drive signal and then monitoring the frequencies at which the phase detector signal indicates zero, to identify the frequency of each of the one or more resonances. A cable compensation control circuit can also be coupled to the duplexing circuit for balancing the reactance of the conductive paths associated with the crystal. This can include a voltage controlled capacitance and a portion of a transformer within the duplexing circuit.
REFERENCES:
patent: 3689747 (1972-09-01), DiMilia et al.
patent: 3864161 (1975-02-01), Thompson
patent: 3967143 (1976-06-01), Wartanabe et al.
patent: 4158805 (1979-06-01), Ballato
patent: 4166784 (1979-09-01), Chapin et al.
patent: 4207836 (1980-06-01), Monaka
patent: 4275363 (1981-06-01), Mishiro et al.
patent: 4311725 (1982-01-01), Holland
patent: 4447782 (1984-05-01), Rutkowski
patent: 4578634 (1986-03-01), Healey, III et al.
patent: 4579083 (1986-04-01), Boivin
patent: 4816743 (1989-03-01), Harms et al.
patent: 4817430 (1989-04-01), Benes et al.
patent: 4888824 (1989-12-01), Anderson et al.
H. Bahadur et al., "Physical Acoustics" Vibrational Modes in Quartz Crystals vol. XVI, 1982, pp. 145 ff.
Leybold Inficon Inc.
Regan Maura K.
Wieder Kenneth A.
LandOfFree
Control circuitry for quartz crystal deposition monitor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Control circuitry for quartz crystal deposition monitor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control circuitry for quartz crystal deposition monitor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-422502